Advice for a nervous newbie

Hi guys, I was hoping I could get some advice from the people on here with more travel background than me (aka everyone!)
Ill try to be brief 🙂

I had planned on travelling with a friend, which has now fallen through. I have no travel background at all, but am determined to give it a shot before I go into full time work. I would massively prefer to be going with friends, but scheduling makes that almost impossible.
I know if I dont go now, I probably never will, so I want to go out solo and see what happens.

I want to go abroad to have a good time, background some different cultures and generally enjoy myself before I start full time work. I dont feel like I need a really challenging travel experience, I admire those who can pull it off, but I feel something laid back will suit my personality more.

I was thinking of visiting Australia/Thailand etc. From what ive heard places like that are well versed travelling routes and will be full of like minded people. Im only really nervous about two things. Firstly, arriving in a city Ive never been in, and being totally alone. I know this may be a bit of a cop out, but does anyone on here have any background starting their travels in some form of organised group? I think there are travel companies that exist that do semi organised tours for young people.
Does anyone have any background in using them? Positive or negative.

My reasoning for thinking about this is that Im slightly worried about arriving somewhere, and not knowing where to start. What hostel to use, which beach to visit, where to meet people etc. In my mind its an easy way to be introduced to other people solo travelling, its a way of easing myself in, and it will ease my fears of turning up in Melbourne or wherever with no friends, no plans and no idea what to do next.

Failing that, does anyone have advice on how to meet other travellers on experiences like this? Ive visited /r/solotravel and its been a great help, but I wondered if anyone on this sub had background using a travel company, and if anyone else was ever worried before their own trip.

Very briefly, Im visiting friends in Dubai until the first week of May. From there I planned to fly to Melbourne, spend maybe 2 months enjoying myself on the East Coast, then hopefully have met some people to visit Thailand with. My budget is around Â£8000 (GBP) which Im hoping will be enough. Ive researched flights and medical jabs, other than that I feel very underprepared. Any advice on where to visit, things to pack, things to avoid and general comments on what Ive posted would be hugely appreciated. This sub has inspired me to go abroad, any final inspiration you can give me would be great. Cheers!!